Lewis Hamilton believes he has a good foundation to start the season with the new Mercedes W04 but says the team needs to keep searching for downforce as it adds updates to the car.

Hamilton got his first proper taste of the car on Friday after his first test day was cut short by a loss of rear brake pressure that resulted in a head-on crash with the barriers. Speaking to the media after his lunch break, Hamilton had completed 59 laps of the Jerez circuit and was happy with his initial impression of the car.

"We have some work to do but it doesn't feel like a disaster," he said. "We're not starting in a bad place. I feel like we have a good platform and a good foundation to work on. I'm definitely going to keep on asking for downforce and hope the guys do a great job.

"We've been able to get the tyres working on the first lap, which they struggled to do last year, but obviously it's quite warm and the track temperature is quite high. I think it's not a bad place for us to start. We definitely need to work and understand the car more, there's a huge amount of work for me to do to fully understand the car before the season."

Asked whether Mercedes' lost mileage at the start of the week would impact the car by Australia, Hamilton added: "I feel like the mileage will count because by the time we get to the end someone will have done 5000 kilometres and we would have done 4000 or something like that. But we're catching up and Nico [Rosberg] did 150 laps yesterday so he already caught half a day up when other people were doing 80 laps. We're probably not going to be able to get to 150 laps today because Nico had already done close to 100 by now. We'll still try to get as much time in as possible."

He said the next step was to work with the factory to improve the weaknesses of the car.

"I think we're at the level we had hoped to be at. I couldn't really ask for more, the guys have done a great job to add downforce to the car and understand where they've been and take the car in the direction they really want to go. Now they need direction and they need me and Nico to tell them where we can improve the car and which direction we need to go. Is it front end we need to improve or is it the rear end? Do we need to improve it globally? Corner exits? Corner entry? That's what we're working on."

Asked if he was impressed by Vettel's lap time of 1:18.565 on hard tyres, which was the fastest of the day at the time, Hamilton said: "I don't know how the hards behave but people seem to be able to get a decent time out of the hards. The Red Bull is always quick so it's not a surprise and it doesn't impress me at all."